1. Field of the Invention
The present invention relates to a manufacturing process of green tea beverages having good flavor, in which deterioration in the color tone and unpleasant precipitates do not occur even during storage for a long time, and in particular, green tea beverages which are most suitable for beverages to be packed in transparent containers.
2. Related Art Statement
As means for increasing the fragrance of green tea beverages, for example, Japanese Patent Laid-open Publication No. Hei 11-262359 discloses methods for fragrance to be given off in which undried tea leaves are roasted in a cauldron. Firing green tea leaves enhances an aroma characteristic of fired tea leaves by heating, improving the flavor of tea.
When green tea leaves are fired, however, such a treatment tends to deteriorate the color tone of the extracted solution. In the case of beverages for packing into transparent containers, in particular, therefore the color tone of drinks is an important aspect of product values and this deterioration has been a serious problem in the production of green tea beverages for packing into transparent containers.
As another means there has been proposed a method for improving the fragrance of green tea beverages by enzyme treatments. For example, Japanese Patent Laid-open Publication No. Hei 4- 228028 discloses methods for producing a tea extract soluble in water having flavor by adding enzyme(s) to residues after tea extraction to hydrolyze, and Japanese Patent Laid-open Publication No. Hei 01-300848 discloses a method for enzyme treating tea leaves in water at 25 to 60xc2x0 C. in the presence of an inert gas.
Enhancement of flavor by such an enzyme treatment, however, results in increasing only a green smell of the low volatile part, causing a problem of losing the balance of the fragrance. In addition, considering actual production lines, any enzyme treatment conventionally disclosed can not be said to be a practical method in any way.
Japanese Patent Laid-open Publication No. Hei 8-126472 discloses a method for mixing extracts of Gyokuro and deeply steamed tea leaves in order to improve the fragrance, and Japanese Patent Laid-open Publication No. Hei 6-343389 discloses a method for extraction at a low temperature in order to prevent off-flavor yielded during pasteurization, the occurrence of, so-called, retort-smell.
However, in the former method, extracts of Gyokuro and deeply steamed tea leaves are simply mixed, and therefore, a long storage may tend to form precipitation and they are not suitable for beverages for transparent containers. On the other hand, although the latter methods allow a retort-smell to be reduced, a long storage may still tend to form precipitation.
As described previously, treatments to enhance the fragrance of green tea beverages by conventional procedures may result in deteriorating the color tone and fragrance of the drinks and losing the balance of the fragrance, and in some cases, also cause the appearance of precipitation during a long storage.
The present invention is to provide a method for producing green tea beverages which have a good flavor and a good balance of aromatic components and in addition, do not form unpleasant precipitates.
In order to achieve the present invention, green tea beverages according to the present invention are produced by a method comprising an extracting step consisting of two extraction steps, a first step in which a pressure extract is obtained by extraction of green tea leaves at an applied pressure (step 1) and a second step in which an atmospheric extract is obtained by extraction of green tea leaves under atmospheric pressure, followed by microfiltration (step 2), and a mixing step in which the pressure and the atmospheric extracts obtained in each step are mixed (step 3).
According to the method for producing tea beverages of the present invention, the pressure extract obtained in step 1 is a solution which has a fragrance suitable for beverages recovered efficiently and in a large amount, whereas it has a tendency of being short of the astringency and umami (delicious taste) characteristic of green tea. On the other hand, the atmospheric extract obtained in step 2 is intense in such astringency and umami, and tends to have a good color tone. By mixing these extracts at an appropriate ratio, the present invention has produced successfully green tea beverages which have a good flavor and a good balance of aromatic components, and in addition, do not cause the appearance of deposits, and are suitable as green tea beverages for packing in transparent containers, in particular, such as so-called PET bottles.